Mechanical link steering systems typically include a knuckle at each wheel. Each knuckle includes a spindle, upper knuckle boss, lower knuckle boss, and mounting flange for connection to a wheel component. King pins extend through openings in the upper and lower knuckle bosses to connect each knuckle to an axle beam. The lower knuckle bosses for each knuckle are configured to receive a tie rod arm. The tie rod arms are connected to each other with a tie rod. In a conventional arrangement, one or both of the knuckles includes a steering arm that is received within the upper knuckle boss. Typically, the driver-side knuckle receives the steering arm. The steering arm is connected to receive steering input from the steering wheel through a steering link referred to as a drag link. As the steering arm steers the driver-side knuckle to execute a turning maneuver, the steering force is transferred to the opposite (passenger-side) wheel through the tie rod.
Hydrostatic steering systems, such as those used for off-highway applications such as tractors, loaders, harvesters, etc., are configured similarly to the mechanical link steering system discussed above, but utilize a steering cylinder input to a cylinder arm instead of a conventional steering arm. Hydrostatic steering systems and some mechanical link steering systems have a steering cylinder/steering link that is installed transversely, i.e. at the bottom of the knuckle on an opposite side of the tie rod arm. This transverse mounting arrangement is usually dictated by the vehicle configuration and packaging constraints.
For solid beam axles, when steering cylinders/steering links are mounted on the opposite side of the tie rod arms, limited attachment configurations are available for use with conventional knuckles. A different forged lower knuckle boss is required to provide bolt holes to attach the steering cylinder/steering link to the knuckle. The tooling for this forging is expensive.